Creep refers to a phenomenon that the strain of a solid material increases with time extension under the condition of keeping constant stress. The creep is different from plastic deformation, the plastic deformation usually occurs after the stress exceeds an elastic limit, but the creep can occur when the stress is smaller than the elastic limit, as long as the action time of the stress is long enough.
The creep phenomenon is very widespread in geotechnical engineering, and a lot of geotechnical engineering disasters are also closely linked with rock and soil creep, such as landslide, collapse, ground subsidence and the like, thus a study on the creep of rock and soil is very necessary and is an important guarantee for the safety of geotechnical engineering.
Previous geotechnical engineering creep tests tend to stay on uniaxial and false triaxial tests, the influence of a confining pressure of a test block is omitted in the uniaxial test, the inequality of pressures in various directions of the test block is omitted in the false triaxial test, and these cannot accurately reflect the true stress and creep behavior of rock and soil under practical conditions. A true triaxial creep test instrument of rock and soil is very rare at home and abroad, the true triaxial creep test instrument is very complicated in structure, relatively large in scale, complicated in operation and high in cost, can only be used in high-strength creep tests, and often loses accuracy on triaxial creep under low-strength conditions. At present, researches on the creep phenomenon of rock and soil under low-strength conditions are deficient.